Characterising compositional intermixing in GaAs/AlGaAs heterostructures using Raman spectroscopy

Summary form only given. Quantum well intermixing (QWI) is attractive as an alternative to regrowth processes, which are the main techniques used in realising photonic integrated circuits. Due to the recent advances in QWI technologies, their use for novel applications, such as patterning asymmetric quantum wells for quasi phase matching applications is being investigated. In such an application, intermixed grating periods <2 /spl mu/m are needed. Although spatially resolved PL measurements have recently been reported for bandgap gratings with similar periods, results showed that there is a lower limit on the size of the period that can be studied. Raman spectroscopy, in contrast, can provide information about many parameters of semiconductor crystals, such as the lattice order and interface stress. The spatial resolution of the Raman scattering measurements is only limited by the laser spot size, since the scattered light is produced only from the part of lattice illuminated by the laser. Raman measurements have served before as a sensitive technique for detecting and studying disordering in GaAs/AlGaAs heterostructures. We show: 1. It is possible to detect compositional intermixing in GaAs/AlGaAs MQW structures, 1 /spl mu/m below the surface, using Raman spectroscopy. 2. Raman spectroscopy can clearly detect periodic bandgap grating structures; fabricated by intermixing. 3. Provisional results on using Raman spectroscopy to quantify the amount of compositional intermixing taking place in GaAs-AlGaAs heterostructures.